Initial testing of the tunable diode laser absorption spectrometer for measuring NO2 and HNO3 in diesel engine exhaust

The Unisearch tunable diode laser absorption spectrometer designed for tropospheric air monitoring (TAMS-2B) was used at the Ontario Research foundation Diesel Dynamometer test facility to make preliminary investigations on the ability of the TAMS-2B to make real time measurements of NO2 and HNO3 in diesel engine exhaust. The results indicated that the TAMS-2B was well suited to making such measurements so long as Teflon filters were employed to remove particles from the exhaust gas stream. The data indicate that at least part of this slow response was due to effects associated with the exhaust train and the dilution tunnel rather than with the TAMS2-B inlet system.